The term Umami, from the Japanese word to describe savory or meaty, is the term used to describe the unique overall fullness, savory or salivatory taste of food. Materials that exhibit this taste quality generally potentiate the intensity of glutamate solutions and this is one important characteristic of umami taste. It is increasingly becoming recognized as the fifth sense of taste, the others being sour, sweet, salt and bitter. Compounds traditionally described as possessing this character are monosodium glutamate (MSG), protein hydrolysates, some amino acids and certain nucleotides and phosphates.
MSG is the most widely used material as a ‘taste enhancer’ where it synergizes the perception of ‘savory’ ingredients, but has also been alleged to cause allergic reaction to a proportion of the population. Since MSG is widely used in Asian cuisine, especially Chinese, this has been referred to as the Chinese Restaurant Syndrome. Free glutamic acid occurs in food but this also is the subject of review by The Federation of American Society for Experimental Biology.
Among other chemical compounds several nucleotides have also been described to exhibit the umami effect Adenosine 5′-(trihydrogen diphosphate), 5′-Cytidylic acid (5′-CMP), 5′-Uridylic acid (5′-UMP), 5′-Adenylic acid (5′-AMP), 5′-Guanylic acid (5′-GMP), 5′-Inosinic acid (5′-IMP) and the di-sodium salts of 5′-Guanylic acid and 5′-Inosinic acid.
Recent literature cites an extensive range of other organic compounds as taste active components of mixtures shown to give the umami taste effect. These include but are not necessarily limited to: organic acids such as succinic acid, lactic acid, saturated straight chain aliphatic acids of six, eight, fourteen, fifteen, sixteen, and seventeen carbon chain lengths, Z4,Z7, Z10,Z13,Z16,Z19-docosahexaenoic acid, Z5,Z8,Z11,Z14,Z17-eicosapentaenoic acid, Z9,Z12,Z16,Z19-octadecadienoic acid, Z9-octadecenoic acid, glutaric acid, adipic acid, suberic acid, and malonic acid. Amino acids having umami effects reported in the literature include glutamic acid, aspartic acid, threonine, alanine, valine, histidine, proline tyrosine, cystine, methionine, pyroglutamic acid, leucine, lycine, and glycine. Dipeptides possessing umami properties include Val-Glu and Glu-Asp.
Other miscellaneous compounds having umami properties include alpha-amino adipic acid, malic acid, alpha-aminobutyric acid, alpha-aminoisobutyric acid, E2,E4-hexadienal, E2,E4-heptadienal, E2,E4-octadienal, E2,E4-decadienal, Z4-heptenal, E2,Z6-nonadienal, methional, E3,E5-octadien-2-one, 1,6-hexanediamine, tetramethylpyrazine, trimethylpyrazine, cis-6-dodecen-4-olide and a number of naturally occurring amino-acids.
The discovery of alkyldienamides in a wide variety of botanicals and the use of some of these to impart flavor and/or a sensation is the subject of a huge amount of literature. Molecules of this type have also been found to exhibit biological activity, most notably anti-bacterial, anti-fungal and insecticidal activity. The most significant compounds in this class, provided with their Chemical Abstract Service number in brackets are: hydroxy-alpha-sanshool [83883-10-7], alpha-sanshool [504-97-2], hydroxy-epislon-sanshool [252193-26-3], gamma-sanshool [78886-65-4], spilanthol [25394-57-4], N-isobutyl E2,E4,8,11-dodecatetraenamide [117824-00-7 and 310461-34-8], isoaffinin [52657-13-3], pellitorine [18836-52-7] and bunganool [117568-40-8] along with a small number of geometrical isomers thereof.
Despite these disclosures there is an ongoing need for new flavor ingredients particularly those that exhibit advantageous organoleptic properties.